Who knew tax preparation could get so controversial? As tax season kicks into gear, archrivals H&R Block and Intuit, maker of TurboTax software, are squabbling like reality show housewives. In the process, they’ve kicked off a contentious social media conversation around our usually unspoken ideas about work, education, and social status.

The bickering began when Intuit rolled out commercials in which customers who use an unnamed tax service (pretty obviously intended to be H&R Block) are horrified to find their tax preparer working as a shopgirl in a clothing store in one of the ads. In another ad, a customer’s tax guy is fixing a clogged pipe under their kitchen sink. “I thought you were a tax expert,” the homeowner says to Bob the plumber as his wife raises her eyebrows and darts out of the room, presumably to go double-check the tax paperwork. (The commercials are here and here.)

H&R Block filed a lawsuit to try to block the commercials. It was unsuccessful; last week, a federal district court judge rejected the request. Company CEO Bill Cobb accused Intuit of “taking cheap shots at hardworking plumbers and retail sales clerks, not to mention millions of Americans holding down two jobs.” Then he took the battle to Twitter.

The company launched a campaign, #iamhrblock, featuring snapshots of its tax preparers holding up signs — many of which say what they do for a living outside of tax season. It’s an eclectic list: air-traffic controller, owner of a power-washing company, Zumba instructor. There are also some whose full-time professions hew a little more closely to our idea of “tax pro” and that go beyond the scope of Intuit’s on-screen portrayals: CPAs, people with MBAs, business and accounting degrees, and Registered Tax Return Preparers.

Regular people, some of them customers of one service or the other, started to weigh in on Facebook and Twitter as well. Some posted criticisms of the TurboTax ads, charging Intuit with being classist or misleading in its portrayal of H&R Block’s workforce. Then came the backlash to the backlash, with others posting messages of derision, questioning just how competent or professional someone can be at tax preparation if they spend most of the year driving a truck, cutting hair, or fixing clogged pipes.

Now, it’s not exactly a big secret that tax prep companies hire a slew of seasonal workers in preparation for the annual filing rush, so why did these commercials touch such a nerve?

It may be because we’re not just debating the merits of having a person versus a software program help you with your taxes. We’re confronting some prejudices about the competence and intelligence levels of people who work certain jobs.

“It plays into a set of biases that are very powerful,” says Anthony P. Carnevale, director and research professor of the Georgetown University Center on Education and the Workforce. We like to think of ourselves as a classless society. Everyone is created equal and all the rest. Most of us would be reluctant to voice the belief out loud that we’re somehow better than people who hold blue-collar or lower-paying jobs. Yet an ad that asks if we want a plumber doing our taxes triggers what Carnevale says are unspoken, sometimes unconscious biases many Americans have about class.

“There’s a tendency for us to suppose that those of us who have sort of can-do jobs, an electrician or a plumber or works in retail or so on, do so because they have less talent, and the evidence doesn’t show that,” he says. But to a large degree (pardon the pun), education has become a proxy for class in our society. “There’s a class distinction in the labor market. Anything you do with a bachelor’s degree is a profession, anything you do with a high school degree is an occupation.”

Given the skyrocketing cost of a college education, it’s likely some people are upset that someone who goes through short-term training and doesn’t take out six-figure loans can earn the title of tax “expert,” especially if that expert spends much of the year employed in a blue-collar field.

And as more people go to college, it increasingly becomes a socioeconomic class marker, in part because it’s become harder to find a job that doesn’t require a bachelor’s degree. “Degree inflation” has increased as changes in education and funding over the past generation have prioritized four-year degrees over vocational and technical programs. “There’s a long tradition in the U.S. of a deep respect for labor,” Carnevale says. “That has shifted as we moved out of a high wage blue-collar economy.”

Mike Rowe, host and job guinea pig of the Discovery Channel’s Dirty Jobs series, made a similar observation in a talk he gave at a 2008 conference. He describes how he showed up for one shoot on a sheep ranch for what we’ll just euphemistically call “animal husbandry.” (The link to his speech is here, but this is a vague description of the job in question for a reason: Like most of Rowe’s show, there is an ick factor, so don’t watch if you’re squeamish.) He says he thought the worker was going about the job the wrong way, based on research he did before the shoot — only to find out his “right” way was totally wrong.

“We’ve declared war on work as a society,” he admits. He takes to task all the factors that reinforce the stereotypes that turn the labor market into a hierarchy, from Hollywood portrayals of blue-collar characters as overweight dopes to commercials that insinuate all of us should be more like the dot-com whiz kid who cashes out to live a life of leisure. “The collective effect of all of that has been this marginalization of lots and lots of jobs,” Rowe says.